YBa_2Cu_3O_(7—δ)超导体中决定Tc的两个内禀因素

Two intrinsic factors for deterrnining Tc in YBa_2Cu_3O_(7-δ)

本文综合报导我们研究组在YBa_2Cu_3O_(7-δ)的元素替代效应研究中所获得的实验结果和从中获得的重要结论。实验结果表明:正交晶体结构、氧含量、Cu的氧化价态,以及金属——半导体(绝缘体)相变等都只是决定Tc的表观因素;存在着CuO_2平面外和CuO_2平面上元素替代的两种不同机制;体系的载流子浓度和CuO_2平面上Cu原子间的动力学的短程反铁磁关联是决定Tc的两个内禀因素。Y系123相双元素替代和Bi系2212相的实验结果进一步证实了上述结论。

Here we report the experimental results and the important conclusions in substituted YBa2Cu3O7-δ systems. It is shown that all the orthorhombic crystalline structure, oxygen content, oxidation state of Cu atoms, and metal-semiconductor (insulator) transition etc. are only the extrinsic factors determining Tc. There are two-type mechanisms of elemental substitution effects outside and within the CuO2 planes. The carrier concentration and the 2D dynamic, short-range antiferromagnetic correlation between Cu atoms in the CuO2 planes are the two intrinsic factors determining the Tc in YBa2Cu3O7-δ. The above conclusions are confirmed further by the results of two-element substituted Y-123 phase and annealed Bi-2212 phase compounds. We consider that it might be a common character for all kinds of high-Tc superconducting oxides.